A U.S. Navy veteran’s mother was denied two visa requests to attend her son’s funeral in Arkansas this past December, according to WREG-TV.

Ngoc Truong, 22, left the Navy in October after serving for four years. He planned to study graphic design in Florida, but was diagnosed shortly after his discharge with leukemia. He died on Dec. 17, 2017.

Truong’s father, Hung Truong, told WREG-TV that he did not know why his ex-wife was denied a visa to travel from Vietnam for the funeral.

The State Department would not provide any further explanation, citing legal confidentiality reasons.